AO3434 N-Channel MOSFET 30V 3.5A SOT-23-3 Equivalent & Substitute Parts

Part Overview

The AO3434 is an N-Channel metal oxide semiconductor field-effect transistor (MOSFET) manufactured by Alpha & Omega Semiconductor Inc., rated for 30V drain-to-source voltage and 3.5A continuous drain current in a surface mount SOT-23-3 package. The device is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing production and maintenance applications. Active alternatives with comparable or enhanced electrical characteristics are available from multiple manufacturers including Diodes Incorporated, onsemi, Nexperia USA Inc., and Rohm Semiconductor.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	30	V
Continuous Drain Current (Id) @ 25°C	3.5	A
On-State Resistance (Rds On) @ 4.2A, 10V	52	mOhm
Gate-Source Threshold Voltage (Vgs(th)) @ 250µA	1.8	V
Gate Charge (Qg) @ 10V	7.2	nC
Input Capacitance (Ciss) @ 15V	340	pF
Power Dissipation (Max)	1	W
Operating Temperature Range	-55 to 150	°C
Package Type	SOT-23-3	—
Mounting Type	Surface Mount	—
RoHS Status	ROHS3 Compliant	—
Moisture Sensitivity Level	1 (Unlimited)	—

Substitute Part Grouping Explanation

Substitution of the AO3434 is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Minimum 30V
Continuous Drain Current (Id): Minimum 3.5A at 25°C
On-State Resistance (Rds On): Maximum 52mOhm at rated current and 10V gate-source voltage
Gate-Source Threshold Voltage (Vgs(th)): Within ±20V maximum gate-source rating
Package Type: SOT-23-3 or equivalent surface mount footprint (TO-236-3, SC-59)
Operating Temperature: Minimum -55°C to 150°C junction temperature range
Compliance: ROHS3 compliant, MSL 1 rating

Substitution Categories:

Parametric Equivalents maintain identical electrical specifications and are direct replacements with no design modifications required. The AO3434LS meets all primary criteria with active product status.

Manufacturer Recommended Substitutes provide enhanced performance characteristics such as increased current rating (4A), improved on-state resistance, or higher power dissipation capability. These include AO3434A, DMG3402L-7, DMG3418L-7, and PMV28ENEAR. These parts are suitable for designs where the enhanced specifications provide additional design margin.

Functional Equivalents maintain voltage and current ratings within acceptable tolerance but may exhibit variations in secondary parameters such as gate charge, input capacitance, or threshold voltage. These include DMG3406L-13, FDN357N, MGSF2N02ELT1G, PMV50ENEAR, and RSR025N03TL.

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On @ 10V (mOhm)	Vgs(th) @ 250µA (V)	Qg @ 10V (nC)	Ciss @ 15V (pF)	Power Diss. (W)	Temp Range (°C)	Package	Status
AO3434	Alpha & Omega	30	3.5	52 @ 4.2A	1.8	7.2	340	1.0	-55 to 150	SOT-23-3	Obsolete
AO3434A	Alpha & Omega	30	4.0	52 @ 4A	1.5	10	245	1.4	-55 to 150	SOT-23-3	Not For New Designs
AO3434LS	Alpha & Omega	30	3.5	52 @ 4.2A	1.8	7.2	340	1.0	-55 to 150	SOT-23-3	Active
DMG3402L-7	Diodes Inc.	30	4.0	52 @ 4A	1.4	11.7	464	1.4	-55 to 150	SOT-23-3	Active
DMG3406L-13	Diodes Inc.	30	3.6	50 @ 3.6A	2.0	11.2	495	0.77	-55 to 150	SOT-23-3	Active
DMG3418L-7	Diodes Inc.	30	4.0	60 @ 4A	1.5	5.5	464.3	1.4	-55 to 150	SOT-23-3	Active
FDN357N	onsemi	30	1.9	60 @ 2.2A	2.0	5.9	235	0.5	-55 to 150	SOT-23-3	Active
MGSF2N02ELT1G	onsemi	20	2.8	85 @ 3.6A	1.0	3.5	150	1.25	-55 to 150	SOT-23-3	Active
PMV28ENEAR	Nexperia	30	4.4	37 @ 4.4A	2.5	8	266	0.66 (Ta), 8.3 (Tc)	-55 to 175	TO-236AB	Active
PMV50ENEAR	Nexperia	30	3.9	43 @ 3.9A	2.5	10	276	0.51 (Ta), 3.9 (Tc)	-55 to 150	TO-236AB	Not For New Designs
RSR025N03TL	Rohm	30	2.5	70 @ 2.5A	2.5	4.1	165	1.0	-55 to 150	TSMT3	Not For New Designs

Engineering Selection Recommendations

Primary Recommendation: AO3434LS

The AO3434LS from Alpha & Omega Semiconductor Inc. is the preferred direct replacement for the obsolete AO3434. This part maintains identical electrical specifications including 30V Vdss, 3.5A continuous drain current, 52mOhm on-state resistance, and 1W power dissipation. The AO3434LS carries active product status, ensuring long-term availability and supply chain stability. All compliance certifications including ROHS3 and MSL 1 rating are maintained. The SOT-23-3 package is identical, requiring no PCB layout modifications.

Secondary Recommendations for Enhanced Performance:

For applications requiring increased current capacity or improved thermal performance, the following active parts provide enhanced specifications:

DMG3402L-7 (Diodes Incorporated) and DMG3418L-7 (Diodes Incorporated) both provide 4A continuous drain current with 30V Vdss and 52mOhm on-state resistance, offering 14% current margin over the AO3434. Both maintain active product status and SOT-23-3 packaging.

PMV28ENEAR (Nexperia USA Inc.) provides the highest current rating at 4.4A with superior on-state resistance of 37mOhm and extended operating temperature to 175°C. This part carries automotive qualification (AEC-Q101) and active product status. The TO-236AB package is mechanically and electrically compatible with SOT-23-3 footprints.

For Current-Limited Applications:

DMG3406L-13 (Diodes Incorporated) provides 3.6A continuous drain current with 50mOhm on-state resistance and reduced power dissipation of 770mW, suitable for applications with thermal constraints. Active product status and SOT-23-3 packaging are maintained.

Parts Not Recommended for New Designs:

AO3434A, PMV50ENEAR, and RSR025N03TL carry "Not For New Designs" status and should be avoided for new product development. FDN357N and MGSF2N02ELT1G have reduced current ratings (1.9A and 2.8A respectively) and are suitable only for applications with lower current requirements.

Frequently Asked Questions (FAQ)

Q: Can the AO3434LS be used as a direct replacement for the AO3434 without design changes?

A: Yes. The AO3434LS maintains identical electrical specifications and SOT-23-3 packaging. No circuit modifications or PCB layout changes are required. The part is a parametric equivalent with active product status.

Q: What is the difference between the AO3434 and AO3434A?

A: The AO3434A provides enhanced specifications with 4A continuous drain current (versus 3.5A), 1.4W power dissipation (versus 1W), and lower threshold voltage of 1.5V (versus 1.8V). However, the AO3434A carries "Not For New Designs" status. For new applications, the AO3434LS is the recommended choice.

Q: Are the Diodes Incorporated DMG3402L-7 and DMG3418L-7 interchangeable?

A: Both parts provide 4A continuous drain current and 30V Vdss in SOT-23-3 packaging. The primary difference is gate charge: DMG3418L-7 has lower gate charge (5.5 nC at 4.5V) compared to DMG3402L-7 (11.7 nC at 10V). Selection depends on gate drive circuit requirements. Both are active products suitable for new designs.

Q: Why is the MGSF2N02ELT1G listed as a substitute if it has only 20V Vdss?

A: The MGSF2N02ELT1G is included in the substitute list provided in the input data. However, the 20V Vdss rating is below the AO3434 specification of 30V. This part is suitable only for applications where the maximum operating voltage does not exceed 20V. For full 30V operation, this part is not recommended.

Q: What is the advantage of the Nexperia PMV28ENEAR over the AO3434LS?

A: The PMV28ENEAR provides superior on-state resistance of 37mOhm (versus 52mOhm), higher continuous drain current of 4.4A (versus 3.5A), and extended operating temperature to 175°C (versus 150°C). The part carries automotive qualification (AEC-Q101) and active product status. The TO-236AB package is mechanically compatible with SOT-23-3 footprints. These enhancements provide additional design margin for high-current or high-temperature applications.

Q: Can I use FDN357N as a replacement for the AO3434?

A: The FDN357N is not recommended as a direct replacement. While it maintains 30V Vdss and SOT-23-3 packaging, the continuous drain current is only 1.9A, which is 46% below the AO3434 specification of 3.5A. This part is suitable only for applications with significantly lower current requirements.

Q: What is the difference between SOT-23-3 and TO-236AB packaging?

A: SOT-23-3 and TO-236AB are equivalent package designations for the same physical form factor. Both refer to a three-lead surface mount package with identical pin spacing and footprint. Parts specified as TO-236AB (such as PMV28ENEAR and PMV50ENEAR) are mechanically and electrically compatible with SOT-23-3 PCB layouts.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed in this reference maintain ROHS3 compliance and MSL 1 (Unlimited) moisture sensitivity rating, consistent with the original AO3434 specifications.

Q: Which substitute part has the lowest on-state resistance?

A: The PMV28ENEAR provides the lowest on-state resistance at 37mOhm at 4.4A and 10V gate-source voltage. This represents a 29% improvement over the AO3434 specification of 52mOhm at 4.2A and 10V.

Q: Is the DMG3406L-13 suitable for applications requiring 3.5A continuous current?

A: The DMG3406L-13 provides 3.6A continuous drain current, which exceeds the 3.5A requirement by 3%. However, the on-state resistance is 50mOhm (versus 52mOhm), providing slightly better performance. This part is suitable for applications requiring 3.5A operation with active product status and SOT-23-3 packaging.

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